Isaiah 6:5-9

5Then said I, Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the LORD of hosts.

6Then flew one of the seraphim unto me, having a live coal in his hand, which he had taken with the tongs from off the altar:

7and he touched my mouth with it, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.

8And I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? Then I said, Here am I; send me.

9And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.